Collective motion in biological systems Andrea Deutsch, Peter Friedl, Luigi Preziosi, Guy Theraulaz To cite this version: Andrea Deutsch, Peter Friedl, Luigi Preziosi, Guy Theraulaz. Collective motion in biological systems. Interface Focus, Royal Society publishing, 2012, 2 (6), pp.689-692. 10.1098/rsfs.2012.0048. hal- 02325148 HAL Id: hal-02325148 https://hal.archives-ouvertes.fr/hal-02325148 Submitted on 5 Nov 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Multi-scale analysis and modelling of collective migration in biological systems Andrea Deutsch1, Peter Friedl2,3,4, Luigi Preziosi5 & Guy Theraulaz6,7,8 1 Dept. Innovative Methods of Computing, Center for Information Services & High Performance Computing, Technische Universität Dresden, Dresden, Germany 2 Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, Netherlands, 3 Cancer Genomics Center, Utrecht, Netherlands 4 Department of Genitourinary Medicine, University of Texas MD Anderson Cancer Center, Houston, United States 5 Department of Mathematical Sciences, Politecnico di Torino, Torino, Italy 6 Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France 7 Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, India 8 Institute for Advanced Study in Toulouse, France Keywords: collective migration; collective behaviour, self-organization; multi-scale analysis; mathematical biology; cancer; biological development; behavioural biology Abstract Collective migration has become a paradigm for emergent behaviour in systems of moving and interacting individual units resulting in coherent motion. In biology, these units are cells or organisms. Collective cell migration is important in embryonic development, where it underlies tissue and organ formation, as well as pathological processes, such as cancer invasion and metastasis. In animal groups, collective movements may enhance individuals’ decisions, facilitate navigation through complex environments and access to food resources. Mathematical models can extract unifying principles behind the diverse manifestations of collective migration. In biology, with a few exceptions, collective migration typically occurs at a “mesoscopic scale” where the number of units ranges from only a few dozen to a few thousands, in contrast to the large systems treated by statistical mechanics. Recent developments in multi-scale analysis have allowed to link mesoscopic to micro- and macroscopic scales, and for different biological systems. The articles in this theme issue on “Multi-scale analysis and modelling of collective migration”, compile a range of mathematical modelling ideas and multiscale methods for the analysis of collective migration. These approaches (i) uncover new unifying organisation principles of collective behaviour, (ii) shed light on the transition from single to collective migration, and (iii) allow 1 to define similarities and differences of collective behaviour in groups of cells and organisms. As common theme, self-organised collective migration is the result of ecological, and evolutionary constraints both at the cell and organismic levels. Thereby, the rules governing physiological collective behaviours also underlie pathological processes, albeit with different upstream inputs and consequences for the group. 1. Introduction Collective migration, the coordinated movement of groups of biological units is observed across a multitude of scales in living systems (Figure 1). At the cellular scale, it plays an essential role in biological development, and the progression of cancer (Friedl and Gilmour, 2009; Rørth, 2009; Weijer, 2009). In particular, collective migration of cohesive cell groups is observed during embryogenesis and is key to the formation of complex tissues and organs. Here, multicellular dynamics form the basis of epithelia, vascular and neuronal structures, with very different resulting shapes and functions. Similar collective cell behaviour is displayed by many invasive cancer types, where detrimental tissue disruption and collective metastasis consequently arise (Cheung and Ewald 2016). Collective migration at the organismic scale is observed in animal species that typically move over long distances and in a periodic manner implying a regular return to the region of departure (Dingle, 1996). The Natal sardine run, is without any doubt, one of the most spectacular examples of collective migration observed in the wild (van der Lingen et al., 2010). It is the second most important animal migration on the planet after that of wildebeest in the Serengeti (Estes, 2014), and it takes place every year from the beginning of May to the end of July along the East coast of South Africa. Millions of sardines (Sardina pilchardus) leave the cold waters of the Cape region to go up north, following the "Benguela" stream which moves up along the coast, to join more temperate waters. Schools of sardines can reach sizes of more than 7 km length, 1.5 km width and 30 meters depth. Collective migrations may be seasonal, but also irruptive and linked to the particular context. Thus, in locusts (Schistocerca gregaria), individual insects adapt their physiology, morphology and behaviour to gregarious life when environmental conditions (rain, abundance of food) become favourable and when their density exceeds the threshold of about 65 winged adults per m2 (Kennedy, 1951; Anstey et al., 2009; Topaz et al., 2012). The adults gather in gigantic swarms with several million insects, which can travel thousands of kilometres, fall on the crops and devastate everything on their path. In each of these scenarios, collective movements require a tight behavioural coordination of individual units, based on the direct, proximate or indirect, mid- or long-range exchange of information between the units (Camazine et al. 2001; Karsenti, 2008; Deutsch et al., 2012; Gloag et al., 2013). Information exchange then influences the behaviour of other individuals of the group at a later point in time, in support of collective coordination or dispersion. Physical and mechanical interactions are also involved in coordinated movements at the cellular level in combination with topographic cues (Trepat et al., 2009; Londono et al., 2014). The fine decoding of the mechanisms governing such collective phenomena has been facilitated by the development of new tracking techniques making it possible to reconstruct with an increasing level of precision the trajectories of cells and organisms in moving groups and over increasingly long periods of time (Oates et al., 2010; Olivier et al., 2010; Dell et al., 2014). High-precision tracking, combined with mathematical modelling has enabled to understand how the non-trivial properties of the collective dynamics emerge at the macroscopic scale from the combined interactions between the units at the microscopic level (Camazine et al., 2001; Vicsek and Zafeiris, 2012; Méhes and Vicsek, 2014). For a long time, conceptually similar research fields evolved independently, i.e., theorizing on how individual behaviour influences collective migration (Couzin et al., 2005; Poujade et al., 2007; Petitjean et al., 2011; Calovi et al., 2014; 2015) or identifying similar collective phases in migrating lymphocyte clusters and fish schools (Calovi et al., 2014; Malet-Engra et al., 2015; Rey- Barroso, 2018). Recent developments in parameterization, modelling, and multi-scale analysis now permit to extract common principles as well as differences between these phenomena at cellular and organismic levels. The overarching goal of this theme issue is to bring together biologists, physicians, physicists and mathematicians in order to meet this challenge. The articles span central facets of studying collective migration phenomena both in cellular and behavioural biology. This includes methodological advances in data analysis to reconstruct the physical and biological interactions between units, integrating strategies to parameterize and quantify collective dynamics of cells, tissues and animal groups, and the development of discrete and continuous mathematical models of collective migration. It is our intention that this issue will become a resource for scientists wishing to learn about the methods and techniques used to investigate collective migration in biological systems, to identify the similarities and differences in the 3 coordination mechanisms at work at the cellular and organismic levels and to shape future interdisciplinary research agendas. 2. Methods and key issues The general methodology used to study collective migration operates at two levels, to monitor and quantify (i) the behaviours of individual units and, in parallel, (ii) the collective organisation and behaviours of the group, and then connect both levels at different scales (micro: individual, meso: group; and macro: whole population), by means of mathematical models (Alt et al., 1997; Cai et al., 2016; Camazine et al.,